The Chemical Constituents of the Organism. 23 



the food ; in the system it is converted into sulphuric acid, 

 and in this form 80 per cent, of the ingested sulphur 

 appears in the urine. The sulphuric acid is united with 

 the bases of the alkaline salts of vegetable acids, which, as 

 just mentioned, are in the body converted by combustion 

 into carbonates. These bases saturate the sulphuric acid, 

 and it has been found experimentally that where the basic 

 salts have been removed from the food, the sulphuric acid 

 produced from the proteid attacks the bases forming part of 

 the living body, and animals so fed die more rapidly than 

 if starved (Bunge). 



The importance of the sulphates in the urine is consider- 

 able ; they afford a passage out of the body for the pro- 

 ducts of proteid change. Phenol and allied compounds are 

 in this way got rid of in the form of phenol sulphate of 

 potassium. Sulphur exists in horn, hair, and epidermis. 



Iron is an important constituent of the complicated 

 proteid haemoglobin. It is also found in the hair, skin, 

 bile, lymph, most body fluids and tissues, and a small quan- 

 tity in the fasces. Bunge considers that the iron which 

 enters the system can only be absorbed when in the form 

 of an organic compound. Inorganic iron, though largely 

 used in the treatment of certain diseases, is not absorbed 

 from the intestinal canal ; food contains only organic and 

 not inorganic iron, and the hemoglobin of the blood is 

 formed from the complex organic compounds of iron which 

 are produced by the vital process of the plant. 



